The present invention relates to an electronic apparatus such as an electronic calculator having a readily handable size. More particularly, the present invention is concerned with an electronic apparatus manufactured on a single flexible insulating plate, such as a polyamide film, in order to provides a substantial reduction in size and simplicity of fabrication.
Recently, the technology for the integrated circuit has been substantially advanced, and accordingly the size of the electronic calculator has been substantially reduced. The computation circuit, the logical control circuit, the storage circuit, the program memory circuit, etc., were all included in the LSI (large-scale integrated circuit). The LSI elements, the display unit and the mechanical contact type keyboard unit were further incorporated on a single solid plate of electrical insulating material, and thus an electronic calculator was fabricated on a single plate such as a glass plate. Copending application Ser. No. 403,857, now abandoned filed Oct. 5, 1973, in the name of Isamu Washizuka, Shintaro Hashimoto and Saburo Katsui, and entitled "Calculator Construction and Method for Making Calculator" discloses a calculator embodying such a technique.
On the other hand, a flexible film such as a film of polyethylene-terephthalate or a film of a polyamide has become useful as a substratum, although the conventional substratum, for example, made from ceramics or an epoxy resin was inflexible. The flexible substratum is suitable for an apparatus which requires a substantial reduction in size. A number of wiring members on the flexible film is formed in a desired pattern by utilizing the metal depositing technology which precipitates or plates metal on such films, the etching technology which eliminates metal attached to such films, and the like.
A new method has been developed in place of the conventional IC package method, wherein an IC chip is mounted on a film plate by utilizing the bonding method, and the output signals therefrom or the input signals thereto are transported via a wiring pattern provided on the film plate. By utilizing a combination of the above-mentioned technologies, an electronic calculator may be provided on a single film when the various kinds of chips are directly mounted on the single film, if a good yield is achieved in the chip bonding technology. The manufacturing processes therefor are suitable for mass production and low cost, since the processes may be automatically controlled by utilizing conventional technology such as the technologies of chip bonding and film cutting.
The concept of an electronic apparatus disposed on a flexible substratum has been already described on pages 13 to 19 of THE ELECTRONIC SCIENCE, VOL. 22, No. 2 published February, 1972 in Japan. The title of the article is "Reduction In Size of An Electronic Apparatus and Print Wiring Technology" by Yoshio Oohara. But, in accordance with the conventional concept, the components which were mounted on the flexble substratum were IC packages or discrete elements, and the mounting thereof was performed by soldering. The soldering positions had to be fixed by the addition of reinforcing plates.
Accordingly, it is an object of the present invention to provide an electronic apparatus equipped or manufactured on a single flexible substratum, the substratum being provided with a wiring pattern thereon, and various kinds of chips mounted on the substratum by utilizing the wireless bonding method.
Another object of the present invention is to provide an electronic apparatus wherein various kinds of chips are mounted directly on small film plates, this is to say, daughter boards, respectively, and the daughter boards are physically connected to a single film plate, that is to say, a mother board, which is provided with a wiring pattern thereon.
Still another object of the present invention is to provide an electronic apparatus wherein the configuration can make best use of the characteristics of an electronic apparatus provided on a flexible substratum.
A still further object of the present invention is to obtain increased production of the above-mentioned electronic apparatus manufactured on a flexible substratum.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
In accordance with the teachings of the present invention, one or more IC chips are directly mounted on a film plate by utilizing the wireless bonding method such as the flip chip bond or the beam lead bond method. Because of the absence of the rigid plate, it is possible to bend the film plate even at the peripheral position thereof on which the chip is mounted. In addition, it is desirable in order to put the concept of the present invention into mass production that the following problems be considered.
(1) How to incorporate the mechanical contact type keyboard unit on the flexible plate as one body?
(2) How to make the best use of the advantages of using the flexible film for the substratum?
(3) How to construct the apparatus taking the yield of the chip bonding into consideration?
Each approach to solve the above-mentioned problems will be disclosed in greater detail hereinafter.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparant to those skilled in the art from this detailed description.